This application makes reference to, incorporates the same herein, and claims all benefits accuring under 35 U.S.C. xc2xa7119 from an application for APPARATUS FOR DELIVERING DEVELOPER OF A LIQUID ELECTROPHOTOGRAPHIC COLOR PRINTER earlier filed in the Korean Industrial Property Office on Aug. 16, 1999 and there duly assigned Serial No. 33735/1999.
1. Field of the Invention
The present invention relates to a wet type electrophotographic color printer, and more particularly to an apparatus for feeding a developing solution of a certain concentration to a developing unit for developing an electrostatic latent image of a photosensitive medium.
Here, it may be noted that the term xe2x80x98printerxe2x80x99 is not limited to a general laser printer only, but includes all kinds of printing apparatuses for printing images by using the electrophotographic method, such as a copier, facsimile machine, etc.
2. Description of the Prior Art
Generally, a wet type electrophotographic color printer prints a desired image by forming an electrostatic latent image by the processes of radiating a laser beam to a photosensitive medium such as a photosensitive belt, then developing the electrostatic latent image formed on the photosensitive medium with a developing solution having a solid toner of a certain color and a liquid carrier as a solvent, and finally transferring the developed form to a printing paper.
Such a wet type electrophotographic color printer may be divided into an engine section and a video controller. Here, the video controller functions to decode data transmitted from a data outputting device such as a computer, or the like, and converts the decoded data into printable form, stores the converted data, and outputs the stored data in the form of serial data for printing after communicating with the engine section.
The engine section includes a photosensitive medium, a charged unit for electrifying the surface of the photosensitive medium at a certain electric potential, an exposure unit for forming the electrostatic latent image on the photosensitive medium by radiating a beam converted in accordance with the electrical data of the to-be-printed portions to the photosensitive medium, a developing unit for developing the latent image of the photosensitive medium by feeding developing solution to the photosensitive medium, a transferring unit for transferring the image of the photosensitive medium to the printing paper, and a developing solution feeder for feeding the developing solution of a certain concentration to the developing unit.
The main part of the wet type electrophotographic color printer constructed as above will be described in detail below. As will be described, in a conventional electrophotographic color printer, condensed ink is discharged from a refill cartridge by compressed air through ink feeding valves to ink storage tanks and carrier is fed to a carrier storage tank. Circulation tanks containing the condensed ink and carrier are maintained at an appropriate concentration by admitting ink from the respective ink storage tanks through ink feeding valves, or carrier from the carrier storage tank, through a carrier feeding valve.
In the developing solution feeder of the conventional wet type electrophotographic color printer, however, since the condensed ink or the carrier stored in the ink storage tanks and the carrier storage tank is fed to the circulation tanks through the ink feeding valves and the carrier feeding valve, the problem arises that the condensed ink or the carrier can not always be fed consistently to the developing solution, leading to an inconsistent concentration of the developing solution. This is because the feeding valves are poorly controllable due to the structure of the feeding valves. Further, the ink feeding valves may have sludge formed in them which results in a narrowed channel for the condensed ink. Accordingly, the image density deteriorates due to the inconsistent concentration of the developing solution which is caused due to the inconstant supply of the condensed ink.
Further, the conventional developing solution feeder employs a refill cartridge using compressed air. This means that the condensed ink or the carrier is jointly stored with the compressed gas in the refill cartridge, which again results in deteriorated image quality and the developing solution may change in concentration due to the condensed ink""s or the carrier""s property change by the compressed air.
Further, since the condensed ink or the carrier is jointly stored with the compressed air in the refill cartridge of the conventional developing solution feeder, the waste developing solution cannot be efficiently collected therein due to the presence of the compressed air.
It is therefore an object of the present invention to provide an improved wet-type electrophotographic color printer.
A further object of the invention is to provide an improved developing solution-feeding apparatus for a wet-type electrophotographic printer.
A yet further object is to provide a developing solution-feeding apparatus which leads to better image quality.
A still further object is to provide a developing solution-feeding apparatus which allows better control of the developing solution concentration.
Another object is to provide a developing solution-feeding apparatus which avoids sludge formation in the ink feeding valves.
Yet another object is to provide a developing solution-feeding apparatus which is simpler.
Still another object is to provide a developing solution-feeding apparatus which does not employ compressed air.
The present invention has been devised to overcome the above problems by providing a developing solution feeder for a wet type electrophotographic color printer capable of appropriately feeding condensed ink or carrier for maintaining a consistent concentration of the developing solution in circulation tanks, while avoiding the possibility of using ink feeding valves and carrier feeding valves.
The present invention also provides a developing solution feeder for a wet type electrophotographic color printer capable of preventing property change of the condensed ink or the carrier basically, which is caused due to compressed air, by using a refill cartridge filled with condensed ink or carrier, purely.
The present invention also provides a developing solution feeder for a wet type electrophotographic color printer capable of feeding the condensed ink or the carrier stored in the refill cartridge to the ink storage tank or the carrier storage tank with one pump, and feeding the condensed ink or the carrier stored in the ink storage tank and the carrier storage tank to the circulation tanks to maintain a consistent concentration of the condensed ink or the carrier.
The present invention provides a color printer having the developing solution feeder which has an improvement as above and achieves the above objects by a developing solution feeding apparatus of a wet type electrophotographic color printer, including: a plurality of circulation tanks for storing developing solution to be fed to a developing unit of the printer, respectively; plurality of injection nozzles for jetting the developing solution stored in the respective circulation tanks to a developing gap of the developing unit, respectively; a plurality of ink storage tanks for storing a condensed ink of a certain color to be fed to the respective circulation tanks; a carrier storage tank for storing a carrier to be fed to the respective circulation tanks; a waste tank for collecting a waste developing solution produced from the respective circulation tanks; a refill cartridge for storing the condensed ink of a certain color or the carrier to supplement the condensed ink or the carrier of the ink storage tanks or the carrier storage tank; developing solution refilling/waste developing solution collecting means for refilling the condensed ink or the carrier of the refill cartridge to the ink storage tanks or the carrier storage tank, and for collecting the waste developing solution in the waste tank to the empty refill cartridge; and ink injecting/constant feeding means for jetting the condensed ink of the refill cartridge to the ink storage tanks during the condensed ink refilling process by the developing solution refilling/waste developing solution collecting means, and for feeding the required amount of the condensed ink stored in the ink storage tanks to the circulation tanks.
Here, the circulation tanks have concentration detecting means for detecting the concentration of the developing liquid stored therein. Further, the ink storage tanks have ink agitators therein which are driven by a single driving source, respectively.
The developing solution refilling/waste developing solution collecting means includes: a common mounting section for mounting the refill cartridge thereon; and a valve unit disposed under the common mounting section to be moved in a vertical and a horizontal direction, and having a plurality of valves to be fitted to an outlet of the refill cartridge. The valve units include four ink feeding valves, a carrier feeding valve, and a waste developing solution valve. The four ink feeding valves are connected to the respective ink storage tanks, the carrier feeding valve is connected to the carrier storage tank; and a waste developing solution valve is connected to the waste tank.
The ink injecting/constant feeding means includes a first ink feeding pipe for connecting a plurality of ink feeding valves formed on the valve unit with the respective ink storage tanks; a second ink feeding pipe branched from the first ink feeding pipe, and connected to the circulation tanks, respectively; a gear pump disposed on the first ink feeding pipe, for jetting the condensed ink of the refill cartridge to the ink storage tanks by a pumping action while being driven in a certain direction, and for feeding the condensed ink of the ink storage tanks to the circulation tanks by the pumping action while being driven in a reverse direction; and back flow preventing means disposed on the first and second ink feeding pipes, and for selectively opening/closing the first and second ink feeding pipes, to thereby prevent a back flow of the ink while the ink is pumped by the gear pump.
According to an embodiment of the present invention, since the condensed ink stored in the refill cartridge is jetted to the ink storage tank by the pumping action of a gear pump, the condensed ink is stored in a refill cartridge, purely, without the presence of compressed air. Accordingly, the property change of the ink due to compressed air, is prevented.
Further, since the condensed ink stored in the ink storage tank is fed to the circulation tanks by a gear pump, the required amount of ink is more precisely fed to the circulation tanks than a conventional structure which employs the constant feeding ink valve .Accordingly, the concentration of the developing solution is precisely and conveniently compensated, and further, the printing quality is improved.
According to another preferred embodiment of the present invention, the developing solution feeding apparatus of a wet type electrophotographic color printer further includes carrier injecting/constant feeding means for jetting the carrier of the refill cartridge to the carrier storage tank during the carrier refilling process by the developing solution refilling/waste developing solution collecting means, and for feeding the required amount of the carrier stored in the carrier storage tank to the circulation tanks.
The carrier injecting/constant feeding means includes a first carrier feeding pipe for connecting the carrier feeding valve of the valve unit with the carrier storage tank; a second carrier feeding pipe branched from the first carrier feeding pipe and connected to the respective circulation tanks; a gear pump disposed on the first carrier feeding pipe, for jetting the carrier of the refill cartridge to the carrier storage tank by the pumping action while being driven in a certain direction, and for jetting the carrier of the carrier storage tank to the circulation tanks by the pumping action while being driven in a reverse direction; back flow preventing means disposed on the first and second carrier feeding pipes, and for selectively opening/closing the first and second carrier feeding pipes, to thereby prevent a back flow of the carrier while the carrier is pumped by a gear pump; and a plurality of opening/closing valves disposed on the circulation tank connecting portions of the second carrier feeding pipe, and for selectively opening/closing the circulation tank connecting portions.
The carrier is stored in the refill cartridge, purely, without the compressed air, and further, the required amount of carrier in the carrier storage tank is fed to the circulation tanks precisely. Accordingly, the property change of the carrier, which is caused due to compressed air in the refill cartridge, is prevented, and the concentration of the developing solution is precisely and conveniently compensated. As a result, the printing quality is improved.
Further, according to another embodiment of the present invention, since the constant feeding ink valve and the constant feeding carrier valve, which are relatively expensive, can be omitted, the manufacturing cost is reduced.
Another above object will be accomplished by a wet type electrophotographic color printer having a photosensitive medium; a charged unit for electrifying the surface of the photosensitive medium at a certain electric potential; an exposure unit for forming the electrostatic latent image on the photosensitive medium by jetting a beam converted in accordance with the electrical data of the to-be-printed portions to the photosensitive medium; a developing unit for developing the latent image of the photosensitive medium by feeding developing solution to the photosensitive medium; a transferring unit for transferring the image of the photosensitive medium to the printing paper; and a developing solution feeder for appropriately feeding the developing solution of a certain concentration to the developing unit.
The developing solution feeder includes a plurality of circulation tanks for storing the developing solution to be fed to the developing unit, and having a concentration detecting device for detecting the concentration of the developing solution stored therein; a plurality of injection nozzles for jetting the developing solution stored in the respective circulation tanks to a developing gap of the developing unit; a plurality of ink storage tanks for storing condensed ink of a certain color to be fed to the respective circulation tanks, and having ink agitators disposed therein to be driven by a single driving source; a carrier storage tank for storing carrier to be fed to the respective circulation tanks; a waste tank for collecting waste developing solution produced from the respective circulation tanks; a refill cartridge for storing the condensed ink of a certain color or the carrier for supplementation of the condensed ink or the carrier to the ink storage tanks or the carrier storage tank; developing solution refilling/waste developing solution collecting means having a common mounting section for mounting the refill cartridge thereon, and a valve unit which is disposed under the common mounting section to be moved in vertical and horizontal directions and is provided with a plurality of valves to be fitted to the outlet of the refill cartridge, for refilling the ink storage tanks or the carrier storage tank with the condensed ink or the carrier of the refill cartridge, and also for collecting the waste developing solution collected in the waste tank to the empty refill cartridge; ink injecting/constant feeding means for jetting the condensed ink of the refill cartridge to the ink storage tanks during the condensed ink refilling process by the developing solution refilling/waste developing solution collecting means, and also for feeding the required amount of the condensed ink stored in the ink storage tanks to the circulation tanks; and carrier injecting/constant feeding means for jetting the carrier of the refill cartridge to the carrier storage tank during the carrier refilling process by the developing solution refilling/the waste developing solution collecting means, and for feeding the required amount of the carrier stored in the carrier storage tank to the circulation tanks.
Accordingly, there is no need to use compressed air in the refill cartridge, and the condensed ink or the carrier stored in the ink storage tank and the carrier storage tank is fed to the circulation tank for consistent concentration of the condensed ink or the carrier in the circulation tank. As a result, the property change of the condensed ink and the carrier, which is caused due to compressed air, is essentially prevented, and the concentration of the developing solution is more precisely maintained.
Additional objects and advantages of the invention will be set forth in part in the description which follows and will be obvious from the description, or may be learned by the practice of the invention.